Vehicle brake



Dec. 13, 1938. G. w. CARLSON a AL 2,140,379

VEHICLE BRAKE I Filed Nov. 27, 1956 #27 2 \7/ i l I I a I l I I IINVENTORS 7 Gasrw A! 6452.90

M ATTORNEYS.

Patented Dec. 13, 1938 UNITED STATES PATENT OFFICE 2,140,379 VEHICLEBRAKE.

Gustav W. Carlson, Cleveland Heights, and Robert 0. Russell, ShakerHeights, Ohio, assignors to Eaton Manufacturing Company,

Cleveland,

4 Claims.

This invention relates to vehicle brakes and more particularlyto animproved brake of the internal expanding self-energizing type.

An object of our invention is to provide an improved self-energizingbrake having a plurality of brake shoes and novel means for actuatingthe same.

Another'object of our invention is to provide an improved brake of thetype mentioned having novel means operable to substantially equalize thebraking action between a plurality of shoes.

Still another object of our invention is to provide an improved brakehaving a pair of shoes between which the braking action is substantiallyequalized and a single pressure fluid responsive device adapted to acton both shoes to apply the same substantially simultaneously.

A further object of our invention is to provide an improved vehiclebrake having a pair of brake shoes and means for actuating the shoesincluding a device operable to apply the shoes and another device forsubstantial equalization of the braking action between the shoes, andwherein drivercontrolled auxiliary means is adapted to act through theequalizing device to apply the shoes. Other objects and advantages ofour invention will be apparent from the following description when takenin conjunction with the accompanying sheet of drawings, in which,

Fig. 1 is a sectional view taken through a vehicle brake embodying ourinvention and showing the friction device thereof in elevation.

Fig. 2 is a transverse sectional view taken through the brake asindicated by line 2-2 of Fig. 1.

Fig. 3 is a partial sectional view taken through one of the anchors asindicated by line 33 of Fig. 1.

Fig. 4 is a similar partial sectional view of a shoe aligning devicetaken on line 44 of Fig. 1.

Fig. 5 is a partial sectional view illustrating another form ofequalizing device which may be embodied in our brake, and

Fig. 6 is a partial transverse sectional view taken on line G-6 of Fig.5.

In the accompanyingdrawing, to which more detailed reference willpresently be made, we have shown one embodiment of our improvedselfenergizing brake,,but it should be understood that this is by way ofexample only andthat the invention may be embodied in various otherdesigns and constructions.

The brake illustrated in this instance includes the usual rotatablebrake drum l0 and a support or backing plate ll adjacent thereto. Thedrum has an annular flange l2 with which a friction device l3cooperates. The friction device may comprise a pair of arcuatelyextending shoes l4. and I5 disposed within the drum for brakingcooperation with the inner surface of the annular drum flange. The shoesare arranged inthe drum so that one pair of adjacent ends I6 and I] maycooperate with an equalizing device l8 and the other pair of adjacentends. I9 and 20 may cooperate with a brake applying or actuator device2|.

The shoesthemselves may be of any suitable construction, for exampleeach shoe may have flange and 'web portions 23 and 24 and may be ofsubstantially T-shaped cross section in which the flange portion 23forms the top of the T-section and the web portion 24' forms the stem ofthe T- section. Each shoe may have a section of suitable brake lining 25secured to the flange portion 23 thereof for frictional cooperation withthe inner surface of the annular .drum flange l2. The shoes are looselysupported adjacent the drum surface so as to have limitedcircumferential shifting and are centered with respect to the drumsurface by means of the aligning devices 26.

Anchors 28 and 29 are provided for the shoes for limitingcircumferential shifting of the friction device during the brakingaction, the anchor 28 cooperating with shoe I 4 and anchor 29cooperating with shoe l5. These anchors may be in the form of abolt-like member 30 carried on the backing plate and having an eccentricpin extension 3| projecting into an opening 32 of the web portion of theshoe. The openings 32 are prefer ably located adjacent the ends l9 and20 of the shoes and each opening. may have an L-shaped bearing member 33therein with which the eccentric pin portion 3| engages.

The actuating device 2| acts on the shoe ends l9 and 20 in a directionto separate the same and press the linings 25 thereof into frictionalengagement with the drum surface. This actuating device may comprise ahousing 35 mounted on the backing plate ll between the opposing shoeends l9 and 20 and may have a fluid pressure cylinder 36 formed therein.A pair of opposed pistons 31 and 38 may be slidably mounted in thecylinder and carry bearing plates 39 which are engaged by cam-likeextensions 40 of the shoe ends I 9 and 20 extending'into the outer endsof the cylinder.

Pressure fluid may be supplied to the section of the cylinder which isincluded between the pis tons by means of a tube or pipe 45 leading froma suitable pressure creating device adapted to be operated by a pedal,lever or other driver-controlled member. Air which collects in thecylinder may be released therefrom through the fitting 42. Leakage ofpressure fluid past the pistons may be prevented by suitable packing inthe form of flexible cup-shaped members 43 which are pressed against theadjacent ends of the pistons by means of acompression spring 44. Entryof dirt and other foreign matter at the outer ends of the cylinder maybe prevented by flexible sealing covers 45 which embrace the cylinderends am: through which the shoe extensions 40 proec a when the brake isto be applied, pressure fluid is forced into the cylinder between thepistons thereof and causes separating movement ofthe shoe ends I! and20. This causes the brake 1in ing to be frictionally pressed against thesurface of the drum flange l2 and, when the drum is rotating in an.ahead direction as indicated by the arrow 41, there is a tendency forthe drum to carry the shoes l4 and I5 along with it in acounter-clockwise direction. This tendency for the drum to carry theshoes along with it produces a self-energizing action which increasesthe braking force. During ahead braking, motion is transmitted from theshoe 14 to the shoe l5 through the equalizing device l8 and the brakingreaction'is taken in part by the equalizing device and in part by theanchor 28. During reverse. braking there isa tendency'for' the shoes l4and I5 to be carried along with the drum in a clockwise direction whenthey are pressed thereagainst by the actuator device and thereactionfrom the resulting braking function is taken against the anchor28.

By means of the equalizing device l8, motionmay be transmited from theshoe, H to the shoe 15 in such 'a manner that the ahead braking actionis substantially equalized between the two shoes. This results in moreuniformwear of the brake linings and mother important advantages beingobtained; This equalizing device; as shown in Figs. 1 and 2, maycomprise a member 49 pivoted on the backing plate H and a link or lever50 cooperating with the adjacent shoe ends I6 and II. The member 49 mayhave a shaft portion 5| journaled in a bearing 52 which is mounted onthe backing plate so as to bring the pivot axis of the shaft portionsubstantially on aradial line of the drumpassing midway between the shoeends l6 and H. The link 50 is carried by the member 49 and as shown inEigs. 1 and 2 may be pivotally connected to this member. at a pointoifset from the-pivot axis of the shaft portion these pins and pivotedthereon. It will be noted,

however, that the bearing blocks 51 and 58 engage the shoe ends atdifferent lever-arm distances from the axis of the pivot pin 58 and thecenter'of the brake drum;

A stop, preferablyvinthe form of a pin 60, is provided on the backingplate to be engaged by the member 49 so as to limitswinging of thismember in a clockwise direction on the shaft portion 5|. When motion istransmitted from the shoe H to the shoe l5 the member 48 engages thestop 8l after which the link 50 swings on the pivot pin 53 to produce awedging or spreading action on the adjacent shoe ends and because of thedifferent lever arm distances mentioned, only about fifty percent of theforce delivered to the link percent being expended against the pivot pin53 and the stop 68. At the beginning of this action so is transmitted tothe shoe I5, the other fifty both of the blocks 51 and 58 are'engaged bythe During reverse braking motion is transmitted from the shoe l5 to theshoe H but since the member 48 can swing away from the stop and the linkcan swing on the pivot pin 58, there is no'equalizing functionaccomplished and the entire braking reaction is taken against, theanchor 28.;-

The actuating device 2| is intended to be regularly used in applying thebrake and therefore may be conveniently termed the service actuator. Itis desirable however to provide, in addition, an auxiliary or emergencyactuating means. We

find that this auxiliary or emergency actuating means may beconveniently arranged to act through the equalizing device I8 and forthis purpose we provide a lever 6| which "is keyed or otherwiseconnected to the outer end of the shaft portion 5| 'of the member 49.Motion may be transmitted to the lever 8| by means of a connecting rod62 extending from a hand lever or other driver-controlled member. Thepulling force applied to the rod 62 swings the lever 8| and the member49 in counter-clockwise direction and the swinging movement therebyimparted to the link or lever 50 causes the bearing blocks 51 and 58 towedge the shoes I4 and I5 apart and. againstthe drum surface.

When the actuating force applied through the device II or through therod 82 is removed the;

shoes I4 and I5 are swung toward each other to a released position inengagement with the anchors 28 and 28. For this'purpose we providesuitable tension springs 63 and which act, respectively, on the shoes I4and I5. The spring 63 is preferably somewhat weaker than the spring64.so that during ahead braking the shoe M will be pressed against thedrum surface slightly in advance of the shoe I5.

In Figs. 5 and 6 of the drawing we have shown another form of equalizingdevice which may be used between the shoes and which will operate toequalize the braking force between the two shoes during reverse brakingas well as during ahead braking. This equalizing device comprises amember 68 pivotally supported on the backing plate by a bearing bracket81 and a link 68 cooperating with the circumferentially aligned radialyoffset shoe ends 88 and 10'. The member 65 isformed with laterallyextending lugs H and 12 which are ofl'set from the axis of thebearingbearing portion 13. The body of the link'is disposed betweentheflugs III and I2 and the fingerlike projections 14 and 15 of thelinkextend outwardly and engage opposite faces of the lugs H and 12.These faces of the lugs are preferably rounded and engage in recesses18. of the link projections. The link 88 is not secured to the member 88but is in rockable relation thereto so that one of the fingers of thelink may fulcrum on one of the lugs while the other finger is capable ofshifting away from the other lug.

In the operation of this equalizing device motion transmitted from theshoe end 69 to the shoe end 10 causes the link 68 to shift relative tothe member 66, the latter remaining stationary with the lug H thereofengaging a stop 'I'I projecting from the backing plate 18. During thisaction the link 68 fulcrums on the lug I l and the link end or finger i5shifts away from the lug 12. It will be noted that the shoe ends 69 and10 engage the link 68 at different lever arm distances from the lug Hwhich is now serving as a fulcrum, and hence only a portion, for examplefifty percent of the force delivered by the shoe end 69 is transmittedto the shoe end 10. During reverse braking, motion transmitted from theshoe end 10 to shoe end 69 causes the link end or finger 14 to shiftaway from the lug H while the link end 15 fulcrums on the lug 12. Inthis case the shoe ends also engage the link at different lever armdistances from the fulcrum 12 such that the force transmitted to theshoe end 69 is approximately only fifty percent of the force deliveredby the shoe end 10.

If desired an emergency or auxiliary brake applying means may beprovided to act through this equalizing device. For this purpose weprovide the pivoted member 66 with a lever 80 which may be operablyconnected with a hand lever or other driver-controlled member. Swingingof the lever 80 in a counter-clockwise direction causes correspondingrotary movement of the member 66 and the link 68 and this rotarymovement causes the shoe ends 69 and I0 to be wedged apart to therebypress the brake shoes against the drum surface. By reason of theconstruction and arrangement of the equalizing device it will be seenthat the braking action will be substantially equalized between the twoshoes during ahead and reverse emergency braking as well as servicebraking, because if the braking torque of one shoe exceeds that of theother shoe it will ing characteristics. In this improved brake only onepressure fluid responsive device is needed to apply the two shoes of thefriction device because our equalizing device acts to substantiallyequalize the braking function betweenthe shoes. It will also be seenthat in our improved brake an auxiliary or emergency connection can beemployed and can be readily made to act on the shoes through theequalizing device. While we have illustrated and described our improvedbrake in a somewhat detailed manner, it should be understood that we donot wish to be limited to the precise details of construction andarrangements of parts illustrated and described, but regard ourinvention as including such changes or modifications as do notconstitute a departure from the spirit of the invention'andthescopeoftheappendedclaims.

Having thus described our invention, we claim:

1. In a brake, the combination of a rotatable drum, a pair of shoesadapted for braking cooperation with the drum and having pairs ofopposed ends, a service actuating means cooperating with one pair ofsaid ends to apply the shoes, means cooperating with the other pair ofsaid ends to substantially equalize the braking action between the shoeswhen applied by said service means, and auxiliary means adapted to actthrough said equalizing means for applying the shoes, said equalizingmeans being also adapted to substantially equalize the braking actionbetween the shoes when they are applied by said auxiliary means.

2. In a brake, the combination of a rotatable drum, a pair of shoesadapted for braking cooperation with the drum, means cooperating withthe shoes adjacent one pair of ends thereof for applying the brake, apivoted member with which the other ends of said shoes cooperate atdifferent lever arm distances, said pivoted member being operable tosubstantially equalize the braking action betweenthe shoes when they areapplied by said means, and means for actuating said pivoted member tothereby apply the shoes independently of the first-named means.

3. In combination, a rotatable drum, a support adjacent said drum, apair of shoes adapted for l braking cooperation with said drum and havitheir ends in opposed paired relation, a service actuator adapted tocooperate with one pair of said ends for applying the shoes for bothahead and reverse braking, means cooperating with the other pair of endsand operable to substantially equalize the braking action between thetwo shoes during both ahead and reverse braking, and emergency operatingmeans adapted to act through said equalizing means for applying'theshoes.

4. In combination, a rotatable drum, a support adjacent'said drum, apair of shoes adapted for braking cooperation with said drum and havingtheir ends in opposed paired relation, 9. service actuator adapted tocooperate with one pair of said ends for applying the shoes for bothahead and reverse braking, a member pivoted onsaid support adjacent theother pair of said ends and having a pair of projections extending inthe direction of its pivot axis but offset therefrom, said other pair ofends being also oflset'irom said pivot axis but a shorter distance thansaid projections, a. part disposed to be engaged on opposite sidesthereof by said oflset ends and extending transversely of the pivot axisbetween said projections, a stop on said support adapted to be engagedby said member for limiting rotation thereof in one direction, said partbeing shiftable relative to said member after engagement of the latterwith said stop and adapted to fulcrum on one of said projections duringahead braking and to fulcrum on the other projection during reversebraking, and emergency member.

GUSTAV w. chanson. ROBERT c. aussmn

